This invention relates to windows and more particularly to heat insulating window units composed of a plurality of sheets of glass spaced apart from each other.
The increasing use of metal frames, particularly aluminium, has given rise to many new window structures. These structures, in endeavours to overcome various problems which have arisen, have become more complex.
These problems have arisen in three main areas: ease of assembly, cost and performance.
The difficulties in assembly are of course related to the cost. The more complex structures require expensive extrusions, hardware, special jigs for manufacture and a considerable number of man-hours.
Costs have risen because of the complexities previously referred to and becuase of the increased quantities of materials that these prior structures have required.
And, finally, these more complex structures have not always led to improved performance. The most common problems have been the insulation factor and the capacity to withstand wide temperature fluctuations. This latter problem has been very prevalent in metal framed glazed building structures with mitred corners since the adjacent components tend to migrate and stress the frame.